| Summary of Significant Classes of Amortizable Intangible Assets |
The following tables provide a summary of our significant classes of amortizable intangible assets: | | | As of December 31, 2015 | | | | | | | | Accumulated | | | | | | | | Cost | | Amortization | | Net | | | | | (Dollars in thousands) | | | Customer lists and contracts | | $ | 20,009 | | $ | (18,914) | | $ | 1,095 | | | Domain and brand names | | | 16,619 | | | (11,200) | | | 5,419 | | | Favorable and assigned leases | | | 2,379 | | | (1,887) | | | 492 | | | Subscriber base and lists | | | 7,313 | | | (3,808) | | | 3,505 | | | Author relationships | | | 2,245 | | | (1,523) | | | 722 | | | Non-compete agreements | | | 1,034 | | | (786) | | | 248 | | | Other amortizable intangible assets | | | 1,336 | | | (1,336) | | | | | | | | $ | 50,935 | | $ | (39,454) | | $ | 11,481 | | | | | As of December 31, 2014 | | | | | | | | Accumulated | | | | | | | | Cost | | Amortization | | Net | | | | | (Dollars in thousands) | | | Customer lists and contracts | | $ | 19,910 | | $ | (16,558) | | $ | 3,352 | | | Domain and brand names | | | 15,465 | | | (9,722) | | | 5,743 | | | Favorable and assigned leases | | | 2,379 | | | (1,795) | | | 584 | | | Subscriber base and lists | | | 4,302 | | | (2,671) | | | 1,631 | | | Author relationships | | | 2,245 | | | (1,379) | | | 866 | | | Non-compete agreements | | | 888 | | | (669) | | | 219 | | | Other amortizable intangible assets | | | 1,336 | | | (1,336) | | | | | | | | $ | 46,525 | | $ | (34,130) | | $ | 12,395 | |
|
| Amortizable Intangible Assets, Estimate Amortization Expense |
Based on the amortizable intangible assets as of December 31, 2015, we estimate amortization expense for the next five years to be as follows: | Year Ending December 31, | | Amortization Expense | | | | | (Dollars in thousands) | | | 2016 | | $ | 3,846 | | | 2017 | | | 2,442 | | | 2018 | | | 2,199 | | | 2019 | | | 1,767 | | | 2020 | | | 982 | | | Thereafter | | | 245 | | | Total | | $ | 11,481 | |
|